Party-line telephone system.



Patented Oct. 22, I90].

W. W. DEAN.

PARTY LINE TELEPHONE SYSTEM.

(Application filed Apr. 28, 1899.)

(No Model.)

"m: Noam vcrsns (20,. VHOYO-LITHO, WASHINGTON, o. c.

UNITED STATES PATENT OFFICE.

WILLIAM W. DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITCH BOARDAND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

PARTY-LINE TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 685,034, dated October22, 1901.

Application filed April 28, 1899- To all whom it may concern.-

Be it known that 1, WILLIAM W. DEAN, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illi- 5 nois,have invented a certain new and useful Improvement in Party-LineTelephone Systems, of which the following is a full, clear, concise, andexact description, reference being had to the accompanying drawing,forming a part of this specification.

My invention relates to a party-line telephone system more particularlyapplicable to a party-line arranged for four subscribers, althoughcertain features of my invention are applicable to a party-linesupplying a different number of subscribers, my object being to providea system wherein a plurality of substations may thus be connected withthe same telephone-line,while calling-signals may be readily sent fromthe central station to any one of the substations.

When four substations are to be connected with a party-line, I connectthe bells or calling devices of two of the substations in series withone of the limbs of the telephone-line, one of the bells being arrangedto respond to a current of one polarity, While the other bell isarranged to respond to a current of opposite polarity. The bellsof theother two subscribers are connected in series in the opposite limb ofthe telephone-line, and one is arranged to respond to a current of onepolarity, while the other responds to a current of the oppositepolarity. The two limbs of the telephone-line are normally connectedwith a third conductor, preferably ground or a common return, andcalling devices are provided at the central station whereby acalling-current of either polarity may be sent over either of the limbsof the telephone-line to thereby ring any ohe of the four bells, asdesired. Means are provided at each substation whereby the circuitthrough the third conductor may be opened when it is desired to talk,the 45 third conductor being thus disconnected from the talking-circuitto prevent the shunting of the current and to prevent staticdisturbances. I preferably provide means whereby the removal of any oneof the telephone-re- 5o ceivcrs from its hook will cut off the connec-Serial No. 714,869. (No model.)

tion with the ground or common return, whereby a completely metallictalking-circuit is provided which will not be disturbed by inductiveeffects. Where only two of the subscribers are connected with theparty-line, the bells may be connected in series with the same limb andarranged to respond to current of opposite polarity, or the bells may beconnected in series with the respective limbs. Likewise, when threesubstations are connected with the party-line two of the bells ofopposite polarity may be connected in series with one of the limbs,while the third bell may be connected in series with the opposite limb.For sending calling-currents from the central station two generators orsources of current of opposite polarity may be employed, with keys forproperly connecting the same in circuit, or a single generator or sourceof current may be employed with keys for connecting one or the other ofthe poles thereof to line to' send the currents of the desired polarity.

I have illustrated my invention in the accompanying drawing, in which Ihave shown the circuit arrangements diagrammatically.

The limbs 1 and 2 of the telephone-line ex tend from the central stationthroughout the several substations A B O D. At the substation A thecalling-bell a is connected in series with the limb 2, and anon-inductive shunt a is provided around the same, wherebytalking-currents will find a ready path nected with a continuation ofthe limb 1.

When the telephone-receiver is removed from its hook, theprimarycircuit, including.

the microphone a battery a and primary a of the induction-coil, isclosed, and the branch circuit through the receiver a and the secondaryof the induction-coil is also closed.

The elevation of the hook by the removal of the receiver alsodisconnects the portions of the limbs 1 and 2 extending beyond thissubstation.

The bell Z] of substation B is connected in series in the limb 2 and inshunt with the non-inductive resistance Z) and is provided withapparatus similar to that described in connection with substation A, theseveral parts being indicated by the letter b, with exponentscorresponding to those employed in connection with substation A.Likewise, the apparatus at substations O and D are indicated by theletters 0 and d with the proper exponents. The bell c at the substationG is connected in series with the limb 1, and bell d at substation D isconnected in series with the limb 1. The contacts (1 and d at the lastsubstation are connected with a third conductor extending to thecalling-generator at the central station, which conductor may be groundor a common return. The bells at substations A and O are illustrated asre spending to a current of one polarity or direction, which I will callpositive, while the bells at substations B and D are illustrated asarranged to respond to currents of opposite polarity ordircction, whichI will term negativc.

The limbs 1 and 2 are illustrated as terminating at the central stationin springs e c, with which the contacts e e of the connecting-plug c areadapted to respectively on gage. In one of the strandsfkeys f f areprovided, while in the other stand f keys 1 are provided. When key f 2is depressed, a generator 9 of positive polarity is connected with thestrand f to send current over limb 2, and when keyf is depressedgenerator g is connected with strand f and limb 1. Likewise, when keyfis depressed generator 9' of negative polarity is connected with thestrand f and limb 2, while the depression of key f connects saidgenerator with strand f and limb 1. Keyf is thus adapted to send currentof positive polarity over strandfand limb 2 through bell ct and groundto thus ring the bell at substation A. The keyf when depressed sends acurrent of negative polarity over strand f and limb 2 through hell I) tothus ring the bell at substation 13. Key f when depressed sends acurrent of positive polarity over strand f 3 and limb 1 through hell 0to thus ring the bell at sub-V Keyj when depressed sends a station 0.current of negative polarity over strand f limb 1 through hell d, thusringing the bell atsubstation D. In this manner calling-currents may besent from the central station to ring the bell of any one of the foursubsta 1 substation with a third conductor, of tele- For clearness Ihave omitted the signaling apparatus for sending signals from the sub-{stations to the central station, since this will tions.

be of the ordinary type heretofore employed in party-line systems.

It will be noted that normallythat is,

' when none of the substation-telephones are connected in circuit-thetwo limbs of the tele phone-line are connected with ground or the thirdconductor, whereby the signaling currents may be sent over either limband the third conductor. Vhen any of the subscribers removes histelephonefrom the hook, the connection with the telephone-line beyondsuch substation is severed and the ground is thus removed from thetalking-circuit, and the talking-circuit becomes wholly metallic,whereby disturbances from inductive effects, due to the presence of aground on the talking-circuit, are obviated.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is-- 1. The combination with a party telephonelinehaving a talking-circuit comprising two limbs, of a third conductornormally connected therewith at the last substation, a hell or calldevice at one of the substations in series in one limb, a hell or calldevice at another of the substations in series in the other limb, meansat the central station for sending current over either limb and thethird conductor and means at each substation for disconnecting saidthird conductor from the talking-circuit-, substantially as described.

2. The combination with a party telephoneline, and a return-conductorfor the callingcurrents normally in circuit therewith at the lastsubstation, of a pair of bells or call devices at the substationsconnected in series in the talking-circuit of the line and arranged torespond to currents of opposite polarity, means at the central stationfor sending current of either polarity over the line and means at eachsubstation for opening the circuit through said return-conductor,substantially as described.

3. The combination with a party telephoneline having a talking-circuitcomprising two limbs, of a third conductor normally connected therewithat the last substation, a pair of bells or call devices at thesubstations con nected in series in one of the limbs and arranged torespond to currents of opposite polarity, a pair of bells or calldevices at the substations connected in series in the other limb andarranged to respond to currents of opposite polarity, means at thecentral station for sending currents of either polarity over either limband the third conductor and means at each substation for disconnectingsaid third conductor from the talking-circuit, substantially asdescribed.

4. The combination with a party telephonelinehavingametallictalking-circuit comprising two limbs normally connected at the lastphone sets at the several substations adapted to be bridged between thetwo limbs of the line, a pair of bells or call devices of relativelyopposite polarity connected in series in one limb,- a pair of bells orcall devices of relatively op posite polarity connected in series in theother limb, means at the central station for sending current of eitherpolarity over either limb and the third conductor and means at eachsubstation for disconnecting said third con- IIG ductor from thetalking-circuit, substantially as described.

5. The combination with a party telephoneline having a metallictalking-circuit comprising two limbs normally connected at the lastsubstation with a third conductor, of telephone sets at the severalsubstations adapted to be bridged between the two limbs of the line, apair of bells or call devices of relatively opposite polarity connectedin series in one of said limbs, a pair of bells or call devices ofrelatively opposite polarity connected in serice in the other limb andmeans at each substation for opening the circuit through said thirdconductor by the act of connecting the telephone set thereat into thetalking-circuit, substantially as described.

6. The combination with a party telephoneline having a talking-circuitcomprising two limbs, of a third conductor normally connected therewithat the last substation, a bell or call device at one of the substationsin series in one limb, a bell or call device at another of thesubstations in series in the other limb, a non-inductive shunt aroundeach bell or call device and means at each substation for disconnectingsaid third conductor from the talking-circuit, substantially asdescribed.

7. The combination with a party telephoneline having a talking-circuitcomprising tWo limbs, a third conductor normally connected therewith atthe last substation, a pair of bells or call devices at the substationconnected in series with one of the limbs and arranged to respond tocurrents of opposite polarity, a pair of bells or call devices at thesubstations connected in series with the other limb and arranged torespond to currents of opposite polarity, a non-inductive shunt aroundeach bell or call device and means at each substation for disconnectingsaid third conductor from the talking-circuit, substantially asdescribed.

In witness whereof I have hereunto subscribed my name in the presence oftwo wit-

